Remember, Google Plus was only released two weeks ago. Somewhere around 9-10 million users have signed up, in two weeks, despite limited availability. That kind of goes beyond “fast” into levels of “wow”, actually. What’s more, it’s projected to reach 20 MILLION USERS by this weekend.

ZDNet reports that the Google Plus One button is already moving up among social plugins. Facebook, with four plugins, remains dominant.

What is surprising, however, is that the Google +1 button (4.5 percent) is already ahead of the Twitter Tweet button (2.1 percent) and the Twitter Follow button (1.3 percent). That means Google is already in second place.

With expanding use of it’s +1 button (which we’re seeing everywhere), and the number of people still waiting impatiently to get invited to the G+ party, you can expect the Google Plus growth rate to stay the same for awhile…